1. Field of the Invention
This invention relates to an ink cartridge for use with an ink jet printer or the like.
2. Prior Art
An ink cartridge IC for holding a dye-based ink, shown in FIGS. 17A and 17B, for instance, includes an ink reservoir (so-called ink tank) filled with an ink absorbent material FA, and an ink delivery block, 26 formed in a bottom of the cartridge in a manner protruding downward therefrom. The ink delivery block 26 is formed with a communication passage 27 extending therethrough into the ink reservoir, and holds an ink absorbent material FB (ink filter) at an inner portion of the communication passage 27. In the above construction, the ink cartridge IC is formed to have a rectangular inner shape so as to hold a larger amount of ink in a space limited in size and at the same time make the cartridge easy to manufacture (mold in one piece). Further, to make the whole ink cartridge compact in size by reducing the size of the protruding block formed in the bottom, the partition wall defining the communication passage 27 is extended into the inner space of the ink reservoir and the ink absorbent material FB is retained inside the inner peripheral surface of the partition wall.
In contrast to the dye-based ink having a coloring matter solved therein, a pigment-based ink contains an insoluble coloring matter (pigment) having a large particle size. Therefore, the pigment-based ink is excellent in light resistance when illuminated after printing, and difficult to fade. On the other hand, the coloring matter (pigment) of the pigment-based ink is dispersed in the ink with particles thereof floating therein, and hence liable to settle out or sediment with the lapse of time. (Although some inks generally classified into xe2x80x9cthe dye-based inkxe2x80x9d contain a coloring matter which settles out, throughout the specification and appended claims, the term xe2x80x9cpigment-based inkxe2x80x9d is used to mean xe2x80x9can ink whose coloring matter settles outxe2x80x9d including the above-mentioned exceptional type of dye-based ink.) Accordingly, when the ink cartridge IC for holding a dye-based ink, described above with reference to FIGS. 17A and 17B, is used for holding a pigment-based ink, sedimentation of the ink proceeds especially in regions filled with ink alone (ink-filled regions) DIa, DIb, to produce an ink having a high coloring matter concentration (i.e. a portion of the above pigment-based ink, which is increased in coloring matter concentration by sedimentation of the coloring matter: hereinafter referred to as xe2x80x9csedimentary inkxe2x80x9d). The sedimentary ink irregularly flows out during printing to cause unevenness of printing such that the printing is carried out e.g. with a high print density immediately after the start of printing, but with a lowered print density thereafter.
It is a first object of the invention to provide an ink cartridge that is capable of supplying a pigment-based ink and at the same time suppressing the mixing of a sedimentary ink into a pigment-based ink supplied, thereby reducing unevenness of printing.
It is a second object of the invention to provide an ink cartridge that is capable of supplying a pigment-based ink and at the same time suppressing the generation of a sedimentary ink even when left unused, thereby reducing unevenness of printing.
It is a third object of the invention to provide an ink cartridge that is capable of supplying a pigment-based ink and at the same time removing a sedimentary ink by initial delivery of the ink after the cartridge is left unused, thereby reducing unevenness of printing.
To attain the first object, according to a second aspect of the invention, there is provided an ink cartridge comprising:
an ink reservoir holding an ink absorbent material therein for storage of a pigment-based ink;
an ink delivery block formed at a lower portion of the ink reservoir, and having a communication passage formed therethrough such that the communication passage extends from an outside of the ink reservoir up to an inner opening of the communication passage which opens into an inside of the ink reservoir, for communication between the outside and the inside of the ink reservoir; and
a sedimentary ink supply-suppressing member for suppressing flow of a sedimentary ink to the inner opening, the sedimentary ink having an increased coloring matter concentration caused by sedimentation of a coloring matter floating in the pigment-based ink.
This ink cartridge includes an ink reservoir holding an ink absorbent material therein for storage of a pigment-based ink, and an ink delivery block formed with a communication passage for communicating between the inside and outside of the ink reservoir. The ink cartridge has the same basic construction as that of the conventional ink cartridge, and when the ink cartridge is left unused, a sedimentary ink is produced. If the ink is delivered as it is, the sedimentary ink is mixed into the ink (pigment-based ink), thereby causing unevenness of printing. Therefore, in order to suppress the mixing of a sedimentary ink into the supplied ink, the ink cartridge has a sedimentary ink supply-suppressing member that prevents flow of a sedimentary ink to the inner opening. This makes it possible to provide an ink cartridge that is capable of supplying a pigment-based ink, and at the same time suppressing the mixing of a sedimentary ink into the supplied pigment-based ink, thereby reducing unevenness of printing.
Preferably, the pigment-based ink is supplied by being drawn in by a predetermined suction force, and the inner opening is arranged above a lowermost bottom surface inside the ink reservoir, the sedimentary ink supply-suppressing member comprising another ink absorbent material different from the ink absorbent material, the another ink absorbent material having an ink-holding force larger than the predetermined suction force, and being arranged in a bottom portion of the ink reservoir at a location lower than the inner opening.
According to this preferred embodiment, while the pigment-based ink is supplied by being drawn in by a predetermined suction force, the inner opening is arranged above the lowermost bottom surface inside the ink reservoir, and hence a sedimentary ink is liable to be generated in a bottom portion of the ink reservoir lower than the inner opening. To cope with this, the ink absorbent material having an ink-holding force larger than the predetermined suction force for supply of the ink is arranged in the bottom portion of the ink reservoir lower than the inner opening, whereby it is possible to hold the sedimentary ink from being delivered as part of the pigment-based ink. This makes it possible to provide an ink cartridge that is capable of supplying a pigment-based ink, and at the same time suppressing the mixing of a sedimentary ink into the supplied pigment-based ink, thereby reducing unevenness of printing.
Alternatively, the inner opening is arranged above a lowermost bottom surface inside the ink reservoir, and the sedimentary ink supply-suppressing member comprises a sedimentary ink receiving member arranged in a bottom portion of the ink reservoir below the inner opening, for receiving the sedimentary ink.
According to this preferred embodiment, the inner opening is arranged above the lowermost bottom surface inside the ink reservoir, and hence a sedimentary ink is liable to be generated in a bottom portion of the ink reservoir lower than the inner opening. To cope with this, a sedimentary ink receiving member is arranged in the bottom portion of the ink reservoir lower than the inner opening for receiving the sedimentary ink, whereby it is possible to hold the sedimentary ink from being delivered as part of the pigment-based ink. This makes it possible to provide an ink cartridge that is capable of supplying a pigment-based ink, and at the same time suppressing the mixing of a sedimentary ink into the pigment-based ink supplied, thereby reducing unevenness of printing.
Alternatively, the sedimentary ink supply-suppressing member comprises a flow slowing lid in intimate contact with the ink delivery block such that the flow slowing lid covers the inner opening, for slowing down flow of the sedimentary ink to the inner opening, and the pigment-based ink is supplied via the flow slowing lid.
According to this preferred embodiment, a flow slowing lid as the sedimentary ink supply-suppressing member is in intimate contact with the ink delivery block such that the flow slowing lid covers the inner opening, for slowing down flow of the sedimentary ink to the inner opening, and the pigment-based ink is supplied via the flow slowing lid. A typical example of the flow slowing lid is a mesh (mesh filter). When passing through the mesh, the sedimentary ink is mixed with other part of the pigment-based ink (having a lower concentration), and the concentration of the sedimentary ink is reduced. This acts to make uniform the concentration of the mixture of the sedimentary ink and other part of the pigment-based ink. This makes it possible to provide an ink cartridge that is capable of supplying a pigment-based ink, and at the same time suppressing the mixing of a sedimentary ink into the pigment-based ink supplied, thereby reducing unevenness of printing.
Alternatively, the sedimentary ink supply-suppressing member comprises an ink filter formed of a predetermined ink absorbent material and held within the communication passage at a location near the inner opening, and a lid joined to a top of the filter for close contact therewith such that the lid covers the inner opening to block the communication passage, and the pigment-based ink is supplied by being drawn in by a predetermined suction force via the ink filter through a gap formed between the lid and the ink delivery block when the lid is pressed upward via the ink filter.
According to this preferred embodiment, the sedimentary ink supply-suppressing member comprises an ink filter formed of a predetermined ink absorbent material and held within the communication passage at a location near the inner opening, and a lid joined to an upper surface of the filter for close contact therewith such that the lid covers the inner opening to block the communication passage. Therefore, when the ink cartridge is left unused, no ink is supplied into the communication passage, and hence no sedimentary ink is generated within the communication passage (no ink-filled region DIb). Further, the pigment-based ink is supplied by being drawn in by a predetermined suction force via the ink filter through a gap formed between the lid and the ink delivery block when the lid is pressed upward via the ink filter. Therefore, even if there is possibility of generation of the sedimentary ink, the sedimentary ink flows through the gap while appropriately mixing with other part of the pigment-based ink having a lower concentration, so that the concentration of the coloring ink is lowered to make uniform the concentration of the whole ink. This makes it possible to provide an ink cartridge that is capable of supplying a pigment-based ink, and at the same time suppressing the mixing of a sedimentary ink into the pigment-based ink supplied, thereby reducing unevenness of printing.
Alternatively, the sedimentary ink supply-suppressing member comprises a plurality of partitions arranged such that the plurality of partitions partially block flow of the coloring matter in a direction of sedimentation thereof, and the ink reservoir is divided by the partitions into a plurality of blocks, such that openings not filled by the plurality of partitions and thereby connecting between adjacent ones of the plurality of blocks are not aligned in the direction of sedimentation of the coloring matter.
According to this preferred embodiment, the sedimentary ink supply-suppressing member comprises a plurality of partitions arranged such that the plurality of partitions partially block flow of the coloring matter in a direction of sedimentation thereof, and the ink reservoir is divided by the partitions into a plurality of blocks, such that openings not filled by the plurality of partitions and thereby connecting between adjacent ones of the plurality of blocks are not aligned in the direction of sedimentation of the coloring matter. In this case, since the plurality of blocks are separated by the partitions, ink flow paths between the blocks are formed by the plurality of openings. The plurality of openings are not aligned in the direction of sedimentation of the coloring matter, and therefore even if the ink cartridge is left unused to cause the coloring matter to settle out, the coloring matter only settles out until they reach the next partition, so that the increase in the concentration of the coloring matter is not large. Further, the ink flow path in each block does not extend in the direction of sedimentation of the coloring matter, but ink flows in a dog-legged manner, so that portions of the ink having different concentrations are appropriately mixed with each other to make uniform the concentration of the mixture. This makes it possible to prevent the concentration of the coloring matter from becoming high. That is, the ink cartridge is capable of suppressing the generation of a sedimentary ink having an extremely high concentration, and supplying a pigment-based ink while reducing unevenness of printing while.
Alternatively, the sedimentary ink supply-suppressing member comprises a plurality of protrusions provided on an inner wall of the ink reservoir, for compressing the ink absorbent material.
According to this preferred embodiment, the sedimentary ink supply-suppressing member comprises a plurality of protruding portions arranged on the inner wall surface of the ink reservoir, for compressing the ink absorbent material. In this case, the ink absorbent material is compressed by the protruding portions arranged on the inner wall surface, so that an ink holding force (ink meniscus force) is increased, whereby it becomes possible to suppress the migration of the ink and the diffusion of the coloring matter, and thereby suppress sedimentation of the coloring matter. Further, even if the sedimentary ink is generated along the inner wall surface, the protruding portions thereon suppress flow of the sedimentary ink, whereby it is possible to provide an ink cartridge that is capable of supplying a pigment-based ink, and at the same time suppressing the mixing of a sedimentary ink into the pigment-based ink supplied, thereby reducing unevenness of printing.
To attain the second object, according to a second aspect of the invention, there is provided an ink cartridge comprising:
an ink reservoir holding an ink absorbent material therein for storage of a pigment-based ink;
an ink delivery block formed at a lower portion of the ink reservoir, and having a communication passage formed therethrough such that the communication passage extends from an outside of the ink reservoir up to an inner opening of the communication passage which opens into an inside of the ink reservoir, for communication between the outside and the inside of the ink reservoir; and
a sedimentary ink generation-suppressing member for suppressing generation of a sedimentary ink having an increased pigment concentration caused by sedimentation of a coloring matter floating in the pigment-based ink, the sedimentary ink generation-suppressing member slowing down flow of a coloring matter within a predetermined sedimentation region where sedimentation of the coloring matter easily proceeds, or flow of the pigment-based ink into the predetermined sedimentation region.
This ink cartridge includes an ink reservoir holding an ink absorbent material therein for storage of a pigment-based ink, and an ink delivery block formed with a communication passage for communicating between the inside and outside of the ink reservoir. The ink cartridge has the same basic construction as that of the conventional ink cartridge, and when the ink cartridge is left unused, a sedimentary ink is produced. If the ink is delivered as it is, the sedimentary ink is mixed into the ink (pigment-based ink) and then delivered, thereby causing unevenness of printing. Therefore, in order to suppress the generation of a sedimentary ink, the ink cartridge has a sedimentary ink generation-suppressing member that prevents or slows down flow (sedimentation) of a coloring matter within a predetermined sedimentation region where sedimentation of the coloring matter easily proceeds, or flow of the pigment-based ink into the predetermined sedimentation region. This makes it possible to provide an ink cartridge that is capable of supplying a pigment-based ink, and at the same time suppressing the generation of a sedimentary ink even when the pigment-based ink is left unused, thereby reducing unevenness of printing.
Preferably, the inner opening is arranged above a lowermost bottom surface inside the ink reservoir, and the sedimentary ink generation- suppressing member is formed by an ink absorbent material having the same properties as the ink absorbent material and being arranged in a manner filling into a portion of the ink reservoir lower than the inner opening.
According to this preferred embodiment, since the inner opening is arranged above the lowermost bottom surface inside the ink reservoir, and a sedimentary ink is liable to be generated in a bottom portion of the ink reservoir lower than the inner opening. To cope with, the ink absorbent material is filled into a portion of the ink reservoir lower than the inner opening, whereby a region filled with ink alone (ink-filled region) can be reduced. This makes it possible to provide an ink cartridge that is capable of suppressing the generation of a sedimentary ink by reduction of an ink-filled region even if the ink cartridge is left unused, whereby when a pigment-based ink is supplied or delivered for printing, unevenness of printing can be reduced.
Alternatively, the inner opening is arranged above a lowermost bottom surface inside the ink reservoir, and the sedimentary ink generation-suppressing member is formed by an ink absorbent material having the same properties as the ink absorbent material and being arranged in an inner bottom portion of the ink reservoir below the inner opening.
According to this preferred embodiment, since the inner opening is arranged above the lowermost bottom surface inside the ink reservoir, and a sedimentary ink is liable to be generated in a bottom portion below the inner opening, of the inner bottom surface of the ink reservoir. Therefore, the ink absorbent material is arranged at the bottom portion below the inner opening, whereby a region filled with ink alone (ink-filled region) can be reduced. This makes it possible to provide an ink cartridge that is capable of suppressing the generation of a sedimentary ink by the reduced ink-filled region even if the ink cartridge is left unused, whereby when a pigment-based ink is supplied or delivered for printing, unevenness of printing can be reduced.
Alternatively, the sedimentary ink generation-suppressing member comprises an ink filter formed of an ink absorbent material larger in size than the inner opening and being forcedly filled into a portion of the communication passage near the inner opening to be held therein, and the pigment-based ink is supplied by being drawn in via the ink filter by a predetermined suction force.
According to this preferred embodiment, the pigment-based ink is delivered by being sucked via the ink filter by a predetermined suction force. In this case, since the size of ink filter is larger than that of the inner opening, the filter is forcedly filled into the communication passage e.g. by compression, to be retained therein. Accordingly, while the ink cartridge is left unused, the ink filter serves as the lid of the communication passage to stop (or reduce) flow of the pigment-based ink into the communication passage. Hence, there is not generated any sedimentary ink within the communication passage. That is, the ink cartridge is capable of suppressing the generation of a sedimentary ink by elimination of an ink-filled region even if the ink cartridge is left unused, whereby when a pigment-based ink is supplied or delivered for printing, unevenness of printing can be reduced.
Alternatively, the sedimentary ink generation-suppressing member comprises an ink filter formed of a predetermined ink absorbent material and being held within the communication passage at a location near the inner opening, and a nail portion provided on the ink delivery block such that the nail portion covers a gap between an inner peripheral surface of the ink delivery block defining the communication passage and the ink filter while urging the ink filter downward, and the pigment-based ink is supplied by being drawn in via the ink filter by a predetermined suction force.
According to this preferred embodiment, the pigment-based ink is delivered by being sucked via the ink filter by the predetermined suction force. In this case, the ink delivery block is provided with the nail portion which covers a gap between the inner peripheral surface of the ink delivery block defining the communication passage and the ink filter to urge the ink filter downward, and hence when the ink cartridge is left unused, the nail portion covers the gap between the inner peripheral surface of the ink delivery block defining the communication passage and the ink filter, and serves as the lid of the communication passage together with the ink filter, thereby reducing supply of ink to the communication passage. Therefore, the generation of a sedimentary ink is suppressed within the communication passage. That is, the ink cartridge is capable of suppressing the generation of a sedimentary ink even if the ink cartridge is left unused, whereby when a pigment-based ink is supplied or delivered for printing, unevenness of printing can be reduced.
Alternatively, the pigment-based ink is supplied in a state in which the ink filter is pressed upward from below, and the ink filter is formed of a laminate of a plurality of types of ink absorbent materials different in resilience from each other.
According to this preferred embodiment, the pigment-based ink is delivered when the ink filter is pressed upward from below. In this case, the ink filter is formed of a laminate of a plurality of types of ink absorbent materials different in resilience from each other, so that it is possible to finely adjust the resilience of the ink absorbent material as a whole.
Alternatively, the sedimentary ink generation-suppressing member comprises an ink filter formed of a predetermined ink absorbent material and arranged within the communication passage at a location near the inner opening, and a filling member for filling a gap between the inner peripheral surface of the ink delivery block defining the communication passage and the ink filter, and the pigment-based ink is supplied by being drawn in via the ink filter by a predetermined suction force.
According to this preferred embodiment, the pigment-based ink is delivered by being sucked via the ink filter by the predetermined suction force. In this case, in addition to the ink filter, the ink delivery block holds the filling material for filling the gap (portion to form an ink-filled region) between the inner peripheral surface of the ink delivery block defining the communication passage and the ink filter. This makes it possible to provide an ink cartridge that is capable of suppressing the generation of a sedimentary ink by elimination of an ink-filled region even if the ink cartridge is left unused, whereby when a pigment-based ink is supplied or delivered for printing, unevenness of printing can be reduced.
Alternatively, the sedimentary ink generation-suppressing member comprises an ink filter formed of a predetermined ink absorbent material and held within the communication passage at a location near the inner opening, and a lid joined to a top of the filter for close contact therewith such that the lid covers the inner opening to block the communication passage, and the pigment-based ink is supplied by being drawn in via the ink filter by a predetermined suction force through a gap formed between the lid and the ink delivery block when the lid is pressed upward via the ink filter.
According to this preferred embodiment, the sedimentary ink generation-suppressing member comprises an ink filter formed of a predetermined ink absorbent material and held within the communication passage at a location near the inner opening, and a lid joined to a top of the filter for close contact therewith such that the lid covers the inner opening to block the communication passage. Therefore, when the ink cartridge is left unused, ink is not supplied to the communication passage, and there is not generated any sedimentary ink within the communication passage. That is, according to this preferred embodiment, the ink cartridge is capable of suppressing the generation of a sedimentary ink by elimination of an ink-filled region even if the ink cartridge is left unused, whereby when a pigment-based ink is supplied or delivered for printing, unevenness of printing can be reduced.
Alternatively, the sedimentary ink generation-suppressing member comprises a plurality of partitions arranged such that the plurality of partitions partially block flow of the coloring matter in a direction of sedimentation thereof, and the ink reservoir is divided by the partitions into a plurality of blocks, such that openings not filled by the plurality of partitions and thereby connecting between adjacent ones of the plurality of blocks are not aligned in the direction of sedimentation of the coloring matter.
According to this preferred embodiment, the sedimentary ink generation-suppressing member comprises a plurality of partitions arranged such that the plurality of partitions partially block flow of the coloring matter in a direction of sedimentation thereof, and the ink reservoir is divided by the partitions into a plurality of blocks, such that openings not filled by the plurality of partitions and thereby connecting between adjacent ones of the plurality of blocks are not aligned in the direction of sedimentation of the coloring matter. In this case, since the ink cartridge has the plurality of blocks divided by the partitions, ink flow paths between the blocks are formed by the plurality of openings. The plurality of openings defined by the respective partitions are not aligned in the direction of sedimentation of the coloring matter, and even if the ink cartridge is left unused to cause the coloring matter to settle out, the coloring matter only settles out until they reach the next partition where the sedimentation is prevented from proceeding. This makes it possible to prevent the concentration of the coloring matter from becoming high. That is, the ink cartridge is capable of suppressing the generation of a sedimentary ink having an extremely high concentration, whereby when a pigment-based ink is supplied or delivered for printing, unevenness of printing can be reduced.
Alternatively, the sedimentary ink generation-suppressing member comprises a plurality of protrusions provided on an inner wall of the ink reservoir, for compressing the ink absorbent material.
According to this preferred embodiment, the sedimentary ink generation-suppressing member comprises a plurality of protrusions arranged on the inner wall surface of the ink reservoir, for compressing the ink absorbent material. In this case, the ink absorbent material is compressed by the protrusions arranged on the inner wall surface, and an ink holding force (ink meniscus force) is increased, thereby making it possible to provide an ink cartridge that is capable of suppressing the migration of ink and the diffusion of the coloring matter, and inhibiting the generation of a sedimentary ink, whereby when a pigment-based ink is supplied or delivered for printing, unevenness of printing can be reduced.
Alternatively, the inner opening opens in a lowermost portion within the ink reservoir such that a bottom surface of the ink reservoir is located above the inner opening, and slopes downward toward the inner opening, and the ink absorbent material is arranged on a whole of the bottom surface.
According to this preferred embodiment, as a sedimentary ink generation-suppressing structure, the inner opening opens in the lowermost surface of the ink reservoir such that the bottom surface of the ink reservoir is located above the inner opening, and slopes downward toward the inner opening. This makes it possible to eliminate a portion corresponding to an ink-filled region, thereby enhancing the ink replacement effect in which one portion of the ink is replaced by another, and even if the ink cartridge is left unused, it becomes difficult for a sedimentary ink to deposit. In addition, the ink absorbent material is provided on the whole bottom surface of the ink reservoir. Therefore, the ink cartridge is capable of suppressing the diffusion of a coloring matter of the ink, and inhibiting the generation of a sedimentary ink, whereby when a pigment-based ink is supplied or delivered for printing, unevenness of printing can be reduced.
To attain the third object, according to a third aspect of the invention, there is provided an ink cartridge comprising:
an ink reservoir holding an ink absorbent material therein for storage of a pigment-based ink; and
an ink delivery block formed at a lower portion of the ink reservoir, and having a communication passage formed therethrough such that the communication passage extends from an outside of the ink reservoir up to an inner opening of the communication passage which opens into an inside of the ink reservoir, for communication between the outside and the inside of the ink reservoir;
wherein the ink cartridge is constructed to accelerate flow of the pigment-based ink from a predetermined sedimentation region wherein sedimentation of a coloring matter easily proceeds toward the inner opening, so as to enable removal of a sedimentary ink having an increased coloring matter concentration caused by the sedimentation of the coloring matter floating in the pigment-based ink, by initial supply of the ink after the ink cartridge is left unused.
This ink cartridge includes an ink reservoir holding an ink absorbent material therein for storage of a pigment-based ink, and an ink delivery block formed with a communication passage for communicating between the inside and outside of the ink reservoir. The ink cartridge has the same basic construction as that of the conventional ink cartridge, and when the ink cartridge is left unused, a sedimentary ink is produced. If the ink is delivered as it is, the sedimentary ink is mixed into the ink (pigment-based ink), thereby causing unevenness of printing. Therefore, in order to make it possible to remove the sedimentary ink by initial delivery of the ink after being left unused, the ink cartridge is constructed to accelerate flow of the pigment-based ink from a predetermined sedimentation region wherein sedimentation of the coloring matter easily proceeds toward the inner opening.
More specifically, if the sedimentary ink generated and accumulated when the ink cartridge is left unused can be removed by an initial delivery of the ink carried out thereafter, there remains only the pigment-based ink exclusive of the sedimentary ink, whereby it is possible to reduce unevenness of printing carried out thereafter. Particularly, in the ink jet printer or the like, after the ink cartridge thereof is left unused, an ink ejection operation (so-called cleaning operation) is carried out to clear nozzles in the print head, and hence if the sedimentary ink can be discharged in the course of this operation, it contributes to reduction of unevenness of printing which can occur after the start of normal printing. That is, the ink cartridge is capable of supplying pigment-based ink, and at the same time removing sedimentary ink by initial delivery of the ink after the ink cartridge is left unused, thereby reducing unevenness of printing.
Preferably, the inner opening opens in a lowermost portion within the ink reservoir such that a bottom surface of the ink reservoir is located above the inner opening, and slopes downward toward the inner opening.
According to this preferred embodiment, the inner opening opens in a lowermost portion within the ink reservoir such that a bottom surface of the ink reservoir is located above the inner opening, and slopes downward toward the inner opening. This construction accelerates the flow of ink from the bottom of the ink reservoir (predetermined sedimentation region within the ink reservoir where the sedimentation of the coloring matter easily proceeds) to the inner opening. Therefore, even if the ink cartridge is left unused, the sedimentary ink is not easily generated, and even when it is generated, it sediments or falls toward the inner opening. Therefore, the ink cartridge is capable of removing the sedimentary ink by initial delivery of the ink after the ink cartridge is left unused, whereby the pigment-based ink can be supplied while reducing unevenness of printing.
Alternatively, the ink supply block holds an ink filter within the communication passage at a location near the inner opening, and the pigment-based ink is supplied by being drawn in via the ink filter by a predetermined suction force, and the ink filter being formed by another ink absorbent material having a smaller ink-holding force than the ink absorbent material.
According to this preferred embodiment, the pigment-based ink is supplied by being drawn in via an ink filter by a predetermined suction force, and the ink filter is formed by another ink absorbent material having a smaller ink-holding force than the ink absorbent material. Therefore, the sedimentary ink in the region filled with the ink alone (predetermined sedimentation region where the sedimentation of the coloring matter easily proceeds; ink-filled regions) is more easily drawn in or sucked than the pigment-based ink (low in concentration of the coloring matter) which is retained by the ink absorbent material with its ink-holding force. Therefore, the ink cartridge is capable of removing the sedimentary ink by initial delivery of the ink after the ink cartridge is left unused, whereby the pigment-based ink can be supplied while reducing unevenness of printing.
The above and other objects, features, and advantages of the invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.